/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.annotation;

import java.lang.annotation.Annotation;
import java.util.Set;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.core.Ordered;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

/**
 * A {@link org.springframework.beans.factory.config.BeanFactoryPostProcessor}
 * implementation that allows for convenient registration of custom autowire
 * qualifier types.
 *
 * <pre class="code">
 * &lt;bean id="customAutowireConfigurer" class="org.springframework.beans.factory.annotation.CustomAutowireConfigurer"&gt;
 *   &lt;property name="customQualifierTypes"&gt;
 *     &lt;set&gt;
 *       &lt;value&gt;mypackage.MyQualifier&lt;/value&gt;
 *     &lt;/set&gt;
 *   &lt;/property&gt;
 * &lt;/bean&gt;</pre>
 *
 * @author Mark Fisher
 * @author Juergen Hoeller
 * @see org.springframework.beans.factory.annotation.Qualifier
 * @since 2.5
 */
public class CustomAutowireConfigurer implements BeanFactoryPostProcessor, BeanClassLoaderAware, Ordered {

    private int order = Ordered.LOWEST_PRECEDENCE;  // default: same as non-Ordered

    @Nullable
    private Set<?> customQualifierTypes;

    @Nullable
    private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

    @Override
    public int getOrder() {
        return this.order;
    }

    public void setOrder(int order) {
        this.order = order;
    }

    @Override
    public void setBeanClassLoader(@Nullable ClassLoader beanClassLoader) {
        this.beanClassLoader = beanClassLoader;
    }

    /**
     * Register custom qualifier annotation types to be considered
     * when autowiring beans. Each element of the provided set may
     * be either a Class instance or a String representation of the
     * fully-qualified class name of the custom annotation.
     * <p>Note that any annotation that is itself annotated with Spring's
     * {@link org.springframework.beans.factory.annotation.Qualifier}
     * does not require explicit registration.
     *
     * @param customQualifierTypes the custom types to register
     */
    public void setCustomQualifierTypes(Set<?> customQualifierTypes) {
        this.customQualifierTypes = customQualifierTypes;
    }


    @Override
    @SuppressWarnings("unchecked")
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        if (this.customQualifierTypes != null) {
            if (!(beanFactory instanceof DefaultListableBeanFactory)) {
                throw new IllegalStateException(
                        "CustomAutowireConfigurer needs to operate on a DefaultListableBeanFactory");
            }
            DefaultListableBeanFactory dlbf = (DefaultListableBeanFactory) beanFactory;
            if (!(dlbf.getAutowireCandidateResolver() instanceof QualifierAnnotationAutowireCandidateResolver)) {
                dlbf.setAutowireCandidateResolver(new QualifierAnnotationAutowireCandidateResolver());
            }
            QualifierAnnotationAutowireCandidateResolver resolver =
                    (QualifierAnnotationAutowireCandidateResolver) dlbf.getAutowireCandidateResolver();
            for (Object value : this.customQualifierTypes) {
                Class<? extends Annotation> customType = null;
                if (value instanceof Class) {
                    customType = (Class<? extends Annotation>) value;
                } else if (value instanceof String) {
                    String className = (String) value;
                    customType =
                            (Class<? extends Annotation>) ClassUtils.resolveClassName(className, this.beanClassLoader);
                } else {
                    throw new IllegalArgumentException(
                            "Invalid value [" + value + "] for custom qualifier type: needs to be Class or String.");
                }
                if (!Annotation.class.isAssignableFrom(customType)) {
                    throw new IllegalArgumentException(
                            "Qualifier type [" + customType.getName() + "] needs to be annotation type");
                }
                resolver.addQualifierType(customType);
            }
        }
    }

}
